Ler uma narrativa medieval com outros olhos: exercícios exploratórios de análise de texto em torno do manuscrito L da Crónica de 1344

Apresentam-se aqui alguns exercícios de exploração das potencialidades de um software de análise de texto, o Voyant Tools, com vista ao desenvolvimento de procedimentos de interpretação quantitativa e qualitativa de uma crónica medieval portuguesa. No caso, utilizámos o manuscrito L da Crónica de 1344, a chamada versão duarteana desse texto. O objetivo deste trabalho será simultaneamente explorar de forma breve as possibilidades de leitura que os softwares deste tipo podem introduzir na análise de textos medievais, assim como olhar criticamente para a complementaridade entre os métodos quantitativos e qualitativos, no quadro de uma análise mais ampla, realizada com recurso às humanidades digitais e dedicada à construção da memória dos espaços na historiografia medieval portuguesa

How social media and DIY culture contribute to democracy, communities and the creative economy

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A Framework for Fast Image Deconvolution with Incomplete Observations

In image deconvolution problems, the diagonalization of the underlying operators by means of the FFT usually yields very large speedups. When there are incomplete observations (e.g., in the case of unknown boundaries), standard deconvolution techniques normally involve non-diagonalizable operators, resulting in rather slow methods, or, otherwise, use inexact convolution models, resulting in the occurrence of artifacts in the enhanced images. In this paper, we propose a new deconvolution framework for images with incomplete observations that allows us to work with diagonalized convolution operators, and therefore is very fast. We iteratively alternate the estimation of the unknown pixels and of the deconvolved image, using, e.g., an FFT-based deconvolution method. This framework is an efficient, high-quality alternative to existing methods of dealing with the image boundaries, such as edge tapering. It can be used with any fast deconvolution method. We give an example in which a state-of-the-art method that assumes periodic boundary conditions is extended, through the use of this framework, to unknown boundary conditions. Furthermore, we propose a specific implementation of this framework, based on the alternating direction method of multipliers (ADMM). We provide a proof of convergence for the resulting algorithm, which can be seen as a "partial" ADMM, in which not all variables are dualized. We report experimental comparisons with other primal-dual methods, where the proposed one performed at the level of the state of the art. Four different kinds of applications were tested in the experiments: deconvolution, deconvolution with inpainting, superresolution, and demosaicing, all with unknown boundaries.Comment: IEEE Trans. Image Process., to be published. 15 pages, 11 figures. MATLAB code available at https://github.com/alfaiate/DeconvolutionIncompleteOb

A convex formulation for hyperspectral image superresolution via subspace-based regularization

Hyperspectral remote sensing images (HSIs) usually have high spectral resolution and low spatial resolution. Conversely, multispectral images (MSIs) usually have low spectral and high spatial resolutions. The problem of inferring images which combine the high spectral and high spatial resolutions of HSIs and MSIs, respectively, is a data fusion problem that has been the focus of recent active research due to the increasing availability of HSIs and MSIs retrieved from the same geographical area. We formulate this problem as the minimization of a convex objective function containing two quadratic data-fitting terms and an edge-preserving regularizer. The data-fitting terms account for blur, different resolutions, and additive noise. The regularizer, a form of vector Total Variation, promotes piecewise-smooth solutions with discontinuities aligned across the hyperspectral bands. The downsampling operator accounting for the different spatial resolutions, the non-quadratic and non-smooth nature of the regularizer, and the very large size of the HSI to be estimated lead to a hard optimization problem. We deal with these difficulties by exploiting the fact that HSIs generally "live" in a low-dimensional subspace and by tailoring the Split Augmented Lagrangian Shrinkage Algorithm (SALSA), which is an instance of the Alternating Direction Method of Multipliers (ADMM), to this optimization problem, by means of a convenient variable splitting. The spatial blur and the spectral linear operators linked, respectively, with the HSI and MSI acquisition processes are also estimated, and we obtain an effective algorithm that outperforms the state-of-the-art, as illustrated in a series of experiments with simulated and real-life data.Comment: IEEE Trans. Geosci. Remote Sens., to be publishe

Semilinear order property and infinite games

Falta resumen y palabras claveEn este trabajo se analiza la determinación de juegos de Lipschitz y Wadge, junto con la propiedad de ordenación semilineal, estrechamente relacionada con estos juegos, en el contexto de la Aritmética de segundo orden y el programa de la Matemática inversa (Reverse Mathematics). En primer lugar, se obtienen pruebas directas, formalizables en la Aritmética de segundo orden, de la determinación de los juegos de Lipschitz y Wadge para los primeros niveles de la Jerarquía de diferencias de Hausdorff. A continuación, se determinan los axiomas de existencia suficientes para la formalización de dichas pruebas dentro de los subsistemas clásicos de la Aritmética de segundo orden (fórmula). Finalmente, en algunos casos se muestra que dichos axiomas de existencia son óptimos, probando que resultan ser equivalentes (sobre un subsistema débil adecuado, como RCA0 o ACA0) a las correspondientes formalizaciones de los principios de determinación o de ordenación semilineal. Los principales resultados obtenidos son los siguientes: Teorema A. Sobre RCA0 son equivalentes: (fórmula) (el principio de determinación para juegos de Lipschitz entre subconjuntos del espacio de Cantor que son diferencia de dos cerrados). (fórmula) (la propiedad de ordenación semilineal de la reducibilidadLipschitz entre subconjuntos del espacio de Cantor que son diferencia de dos cerrados). Teorema B. Sobre RCA0 son equivalentes: (fórmula) (el principio de determinación para juegos de Lipschitz entre subconjuntos abiertos o cerrados del espacio de Baire). Teorema C. Sobre ACA0 son equivalentes: (fórmula) (el principio de determinación para juegos de Lipschitz entre subconjuntos del espacio de Baire que son simultáneamente abiertos y cerrados). (fórmula) (la propiedad de ordenación semilineal de la reducibilidadLipschitzentre subconjuntos del espacio de Baire simultáneamente abiertos y cerrados).In this thesis we analyze the determinacy of the Lipschitz and Wadge games, as well as the tightly related semilinear ordering principle, in the setting of second order arithmetic and of the program of Reverse Mathematics. Firstly, we obtain direct proofs, formalizable in second order arithmetic, of the determinacy of Lipschitz and Wadge games for the first levels of the Hausdorff's hierarchy of differences. Then we determine the set existence axioms needed to formalize such proofs within the classical subsystems of second order arithmetic (fórmula). Finally, in some cases we show that these axioms of existence are optimal, proving that they turn out to be equivalent (over a suitable weak subsystem asRCA0 orACA0) to the corresponding formalization of the principles of determinacy or semilinear ordering. The main results are: Theorem A.The following assertions are pairwise equivalent over RCA0: (fórmula) (determinacy of Lipschitz games for subsets of the Cantor space which are differences of closed sets). (fórmula) (Lipschitz semilinear ordering for subsets of the Cantor space which are differences of closed sets). Theorem B.The following assertions are pairwise equivalent over RCA0: (fórmula) (determinacy of Lipschitz games for open or closed subsets of the Baire space). Theorem C.The following assertions are pairwise equivalent over ACA0: (fórmula) (determinacy of Lipschitz games for clopen subsets of the Baire space). (fórmula) (Lipschitz semilinear ordering for clopen subsets of the Baire space)

Ser estudante de doutoramento: A relação de orientação e a perceção de desenvolvimento pessoal

O presente estudo procurou analisar o impacto da relação de orientação doutoral (ao nível do tipo de relação e qualidade percebida da relação) na perceção de desenvolvimento pessoal (em termos de ganhos e perdas). Participaram neste estudo 308 estudantes de doutoramento de três universidades portuguesas. Foram utilizados três questionários: Questionário de Interação Estudante-Orientador/a (QIEO, acerca do tipo de relação; adaptado de Mainhard, van der Rijst, van Tartwijk, & Wubbels, 2009); Questionário de Relação com o/a Orientador/a (QRO, acerca da qualidade da relação; Melo, 2000) e o Questionário Processo de Doutoramento: Ganhos e Perdas (PDGP, sobre a perceção de ganhos e perdas desenvolvimentais; adaptado de Melo, 2000). Foram encontradas relações de influência entre a qualidade da relação e o tipo de relação sobre a perceção de ganhos e perdas

Aspectos de pragmaticalização de marcadores discursivos no alemão e no português

In this article, I discuss the syntactic, semantic and discursive roles of conjunctions as discourse markers in German and Portuguese (wobei, weil and obwohl; porque and que). I also provide some evidence for the process of grammaticalization/pragmaticalization in which these markers are involved. This study is part of a broader contrastive-analysis project which aims to investigate the grammaticalization process of complex sentences in German and Portuguese from a cognitive-discursive perspective.Neste artigo, discute-se o papel discursivo, semântico e sintático dos marcadores discursivos de origem conjuncional do alemão e do português (wobei, weil e obwohl; porque e que) e enumeram-se algumas evidências a respeito do processo de gramaticalização/ pragmaticalização desses marcadores em ambas as línguas. O estudo faz parte de um projeto de análise contrastiva dos processos de gramaticalização das sentenças complexas do alemão e do português e toma como base uma perspectiva teórica cognitivo-discursiva